title: Segrosome assembly at the pliable parH centromere.
abstract: The segrosome of multiresistance plasmid TP228 comprises ParF, which is a member of the ParA ATPase superfamily, and the ParG ribbon-helix-helix factor that assemble jointly on the parH centromere. Here we demonstrate that the distinctive parH site (∼100-bp) consists of an array of degenerate tetramer boxes interspersed by AT-rich spacers. Although numerous consecutive AT-steps are suggestive of inherent curvature, parH lacks an intrinsic bend. Sequential deletion of parH tetramers progressively reduced centromere function. Nevertheless, the variant subsites could be rearranged in different geometries that accommodated centromere activity effectively revealing that the site is highly elastic in vivo. ParG cooperatively coated parH: proper centromere binding necessitated the protein's N-terminal flexible tails which modulate the centromere binding affinity of ParG. Interaction of the ParG ribbon-helix-helix domain with major groove bases in the tetramer boxes likely provides direct readout of the centromere. In contrast, the AT-rich spacers may be implicated in indirect readout that mediates cooperativity between ParG dimers assembled on adjacent boxes. ParF alone does not bind parH but instead loads into the segrosome interactively with ParG, thereby subtly altering centromere conformation. Assembly of ParF into the complex requires the N-terminal flexible tails in ParG that are contacted by ParF.
authors.affiliation: Faculty of Life Sciences and Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK.
authors.forename: Meiyi
authors.initials: M
authors.lastname: Wu
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Zampini
authors.forename: Malte
authors.initials: M
authors.lastname: Bussiek
authors.forename: Christian
authors.initials: C
authors.lastname: Hoischen
authors.forename: Stephan
authors.initials: S
authors.lastname: Diekmann
authors.forename: Finbarr
authors.initials: F
authors.lastname: Hayes
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002503:Centromere / Q000737:chemistry / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D009875:Operator Regions, Genetic; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins